Organic material stabilized with benzyl ethers



United States Patent Int. Cl. C081? 45/58; C10m 1 38; A23d 5/04 U.S. Cl.252-48.2 20 Claims ABSTRACT OF THE DISCLOSURE Organic material isstabilized by dihydrocarbylhydroxybenzyloxy alkanes includingthiobenzyloxy analogs and hydroxyand mercaptan-substituted alkanes.

This is a division of application Ser. No. 135,428, filed Sept. 1, 1961,now U.S. 3,346,648.

This invention relates to novel and useful chemical compounds and thepreparation and uses thereof. Specifically, this invention relates todialkyl hydroxy benzyl ethers, their preparation from dialkyl phenolsand their uses as antioxidants.

Phenolic compounds have found utility as antioxidants in various organicmedia. In general, they have been found to have a high degree ofspecificity. Thus, compounds effective in one medium are often found tohave no effect or even a deleterious effect in other media. Further,even in the same media the effectiveness of an antioxidant is greatlyinfluenced by the environment. Thus antioxidants effective at lowtemperatures are often found ineffective when exposed to hightemperatures. Also in the processing of various media, such as rubberand the synthetic polymens, many antioxidants otherwise effective arecompletely useless due to their volatility. Applicant, however, hasdiscovered a certain class of phenolic compounds which, contrary to theproperties of phenolic compounds in general, are effective antioxidantsin a large and varied range of organic media. Further, the volatilityand stability of a-pplicants compounds are such that they are highlysuitable for use in media which are to be subjected to high processingtemperatures.

Another problem often encountered in the antioxidant art is that ofstaining and discoloration. This problem especially manifests itself inthe rubber and synthetic polymer areas where discoloration and stainingof the product precludes commercial acceptance. This problem iseffectively solved by the use of applicants compounds. Not only are theyeffective antioxidants but they operate with a minimum of discolorationor staining.

It is, therefore, an object of this invention to provide novel anduseful chemical compounds. Another object is to provide novel and usefuldialkyl hydroxy benzyl ethers. A further object is to provide a processof preparing the novel benzyl ethers of this invention. A still furtherobject is to provide improved compositions of matter containing thevarious compounds of this invention. A specific object is to providerubber stabilized against oxidative deterioration. Other importantobjects of this invention will be apparent from the followingdescription.

According to this invention the above and other objects are accomplishedby providing, as a new composition of matter, a compound having theformula l X2 is H @CX1Rs-X R5 H HO X4 R4 b wherein R and R are eachindependently selected from the group consisting of alkyl radicals offrom 1-12 carbon atoms, cycloalkyl radicals of from 5-8 carbon atoms,aralkyl radicals of from 6-11 carbon atoms, aryl radicals of from 610carbon atoms and alkaryl radicals of from 7-15 carbon atoms; R R and Rare each independently selected from the group consisting of hydrogenand groups having the formula II R1 H O H HO X X X and X; are eachindependently selected from the group consisting of oxygen and sulfur; aand b are each independently selected from integers having the value 0to 1; and R is an aliphatic hydrocarbon of from 2-6 carbon atoms and isdivalent when a and b are 0, trivalent when a plus b is 1 andtetravalent when a plus b is 2, said valencies being on different carbonatoms, that is, no more than one oxygen or sulfur is on any singlecarbon atom.

Examples of the compounds of this invention include:

1,2,3-tris [3- (p-ethylbenzyl) -4-hydroxy-5-(p-n-propylbenzyl)benzyloxy] -4- 3- (p-ethylbenzyl) -4-hydroxy-5-(p-npro pylbenzyl) benzylthio] -n-butane;

1,4-bis 3- (a-methylbenzyl -5-n-butyl-2-hydroxybenzyloxy]-2-hydroxymethyl-3-n1ercaptomethyl-n-butane;

1,3-bis (3 ,5-dibenZyl-4-hydr0xybenzyloxy) -2- 3,5-dibenzyl-4-hydroxybenzylthiomethyl) -n-propane;

l, 2,3-tris 3,5 -di-n-dodecyl-2-hydroxybenzyloxy -n-propane;

1, 3-bis 3-p-n-amylphenyl-5-p-n-nonylphenyl-4-hydroxybenzyloxy)-n-propane;

1-( 3 -n-amyl-5-cycloheptyl-2-hydroxybenzyloxy) -4-3-namyl-S-cycloheptyl-2-hydroxybenzylthio) butane;

1,3-bis (3 ,5-di-p-n-hexylphenyl-4-hydroxybenzyloxy) -2,2-

bis 3 ,5 -dip-n-hexylphenyl-4-hydroxyb enzyloxymethyl -n-pro pane;

1,6-bis 3-benzyl-5-cyclohexyl-2-hydroxybenzylthio) -2,4-

dihydroxy-n-hexane 1, 2,5 -tris 3 2-hexyl) -4-hydroxy-5-1-naphthyl)benzylthio] -4-hydroxy-n-pentane;

1,2,3-tris 3,5 -dicyclooctyl-2-hydroxybenzylthio) -n-propane;

1,2,3-tris 3-(a,a-dimethylbenzyl) -5-n-decyl-4-hydroxybenzylthio] -5- 3-a,a-dimethylbenzyl) -5-n-decyl-4- hydroxybenzyloxy] -n-pentane;

l- (3 -cyclooctyl-S-n-heptyl-Z-hydroxybenzyloxy) -6- mercapto-n-hexane;

1,2-bis (3 -m-n-heptylphenyl-4-hydroxy-5-o-n-octylphenylbenzyloxy)-n-propane;

1- 3- a,a-diethylbenzyl) -2-hydroxy-5-n-octylbenzyloxy]2,2-dihydroxymethyl-n-butane; and

1,2,3,4-tetnakis 4-hydro-xy-3-p-methylphenyl-5-n-nonylbenzylthio-n-butane.

A preferred embodiment of this invention consists of compounds ofFormula I wherein a and b are and R is ethylene. These are preferredbecause of their ease of preparation from readily available startingmaterials and their excellent antioxidant properties. Among the compounds represented by this preferred embodiment are:

3 3 -dodecyl) -4-hydroxy-S-n-octylbenzylthiohydroxyethane;

bis 3,5 -di-tert-butyl-4-hydroxybenzylthio) ethane;

3-benzyl-2-hydroxy-S-methylbenzylthiohydroxyethane; bis 3-cyclohexyl-5-ethyl-4-hydroxybenzylthio ethane;

3- a-ethyl-a-methylb enzyl) -2-hydroxy-5(Z-n-undecyl)benzyloxymercaptoethane;

bis (4-hydroxy-3-p-ethylphenyl-5-n-propylbenzyloxy) ethane; and

3,5-dicyclopentyl-Z-hydroxybenzyloxyhydroxyethane.

A particularly preferred embodiment of this invention consists ofcompounds having the formula wherein X and X are as described followingFormula I, R; is an alkyl group of from 1-12 carbon atoms, R is analpha-branched alkyl group of from 3-l2 carbon atoms and R is selectedfrom the group consisting of hydrogen and groups having the formula IV.R7

These compounds are particularly preferred because of their excellentstability and their superior antioxidant properties. Among the compoundsrepresented by this embodiment are:

3,5-di-tert-butyl-4-hydroxybenzylthiomercaptoethane;

bis(3-tert-butyl-4-hydroxy-S-methylbenzylthio) ethane;

3-tert-amyl-4-hydroxy-5-(2-nonyl)benzylthiohydroxyethane;

3-see-butyl-4-hydroxy-5-methylbenzyloxy-3'-secbutyl-4'-hydroxy-5'-methylbenzylthioethane;

3-(4-dodecyl)-5-n-hexy1-4-hydroxybenzylmercaptoethane; and

bis[3-n-heptyl-4-hydroxy-5-(3-n-undecylbenzyloxy] ethane.

A further particularly preferred embodiment of this invention consistsof compounds of Formula III wherein R is a group of Formula 1V andwherein X and X; are both oxygen. These compounds are the mostparticularly preferred because they have excellent stability, lowvolatility, are most superior antioxidants and can be incorporated intoa wide range of organic media. Among the compounds represented by thisembodiment are:

3,5-di-tert-butyl-4-hydroxybenzoyloxyhydroxyethane; bis 3 ,5-di-tert-butyl-4-hydroxyb enzyloxy) ethane;3-tert-butyl-4-hydroxy-S-methylbenzyloxyhydroxyethane; bis(3-tert-butyl-4-hydroxy-S-methylbenzyloxy) ethane;4-hydroxy-3,S-diisopropylbenzyloxyhydroxyethane;

and his 4-hydroxy-3,5 -diiso p ropylb enzyloxy) ethane.

The particular compounds,bis(3,5-di-tert-butyl-4-hydroxybenzyloxyJethane and 3,5di-tert-butyl-4-hydroxybenzyloxyhydroxyethane have been found byapplicant to be highly effective non-staining, non-discoloring,nonvolatile compounds which are compatible with a wide variety oforganic media. Accordingly, these compounds are the most particularlypreferred embodiments of this invention.

The compounds of this invention can be produced by the reaction of aphenol having the formula V. OH

wherein R is as described following Formula I and R and R are eachindependently selected from the group consisting of hydrogen and R suchthat one of R and R is hydrogen and the other is R with formaldehyde anda compound selected from the group consisting of polyhydric alcohols,polythiols and hydroxythiols; said compounds having the formula whereinR X X X X a and b are as described following Formula I; in the presenceof a catalytic quantity of a metallic hydroxide condensation catalyst,said metallic hydroxide being of a metal selected from the groupconsisting of alkali and alkaline earth metals.

In the above reaction variations in reaction time and reagentconcentration will affect the amount of phenolic groups resultingcompound. If the reaction is allowed to go to completion essentially allthe hydroxyl or mercapto groups will be reacted yielding a polybenzylether in which the number of benzyl moieties present would be equal tothe number of hydroxyl or mercapto groups present in the reactant.

If, however, it is desired to produce substantial amounts of benzylethers which contain one or more hydroxyl or mercapto groups on thealiphatic hydrocarbon portion, said benzyl ether should be removed priorto the reaction going to completion. Accordingly, another embodiment ofthis invention is the process of preparing such benzyl ethers byreacting a phenol having the formula VII. (3H

wherein R R and R are as described above; with formaldehyde and acompound selected from the group consisting of polyhydric alcohols,polythiols and hydroxythiols; said compounds having the formula VIII. 1

wherein R X X X X a and b are as described above; in the presence of acatalytic quantity of a metallic hydroxide condensation catalyst; saidmetallic hydroxide being of a metal selected from the group consistingof alkali and alkaline earth metals; and removing said benzyl ether.

The various reactants employed in the above reactions are well known inthe art. The aliphatic hydrocarbons containing mercapto groups used inthe above reactions can be prepared from the corresponding halogenatedhydrocarbon by reacting it with potassium hydrogen sulfide. Thus,1-hydroxy-2-chloroethane can be reacted with potassium hydrogen sulfideto produce monothioethylene glycol. Likewise, 1,6 dichloro2,4-dihydroxy-n-hexane can be reacted with potassium hydrogen sulfide toproduce 1,6- dimercapto-2,4-dihydroxy-n-hexane. Also 1,2,3,-trichlr0-propane can be reacted with potassium hydrogen sulfide to produce 1,2,3trimercaptopropane. The preparation of other reactants used in theperformance of applicants invention will be apparent to those skilled inthe art.

The above reactions can be conducted with or without a solvent by usingan excess of the lower melting alcohols or thiols such as ethyleneglycol or monothioethylene glycol. No solvent need be used, the thiol oralcohol itself acting both as reactant and solvent. With the highermelting thiols or alcohols such as propylene glycol or pentaerythritol asolvent should be used. In these latter reactions, stoichiometricamounts of alcohol or thiol can be used. However, in many reactionsyields will be enhanced when using an excess of the alcohol.

Suitable solvents are dioxane, dimethylformamide and the higher boilingethers such as di-n-propyl ether, ethyln-butyl ether, di-n-amyl ether,diisoamyl ether, di-n-hexyl ether, anisole and diphenyl ether. Ifpressure or lower temperatures are used, the lower boiling ethers suchas diethyl ether, diisopropyl ether and methyl-n-butyl ether can also beused.

The temperatures employed with the reaction vary from about 20 C. to thereflux temperature of the highest boiling solvent or reactant, about 260C., with reaction times of from one half hour to 2 weeks or more to givea good yield of product. A preferred temperature range is from about 70C. to about 200 C. This temperature range gives an excellent yield ofproduct in a convenient length of time. i

The metallic hydroxide condensation catalyst is employed in catalyticquantity. This quantity ranges from about 1 to about 50 percent byweight based on the Weight of the phenol used in conducting the process.Deviations from these ranges of proportions are permissible,particularly when an excess of alcohol is employed. The alkali metalhydroxide catalysts include lithium hydroxide, sodium hydroxide,potassium hydroxide, rubidium hydroxide and cesium hydroxide. Thealkaline earth metallic hydroxides used as catalysts in the process ofthis invention include magnesium hydroxide, calcium hydroxide, strontiumhydroxide and barium hydroxide. Mixtures of these catalysts can be used,especially mixtures of a plurality of alkali metal hydroxides oralkaline earth metal hydroxides. Of the foregoing hydroxides, sodiumhydroxide, potassium hydroxide and calcium hydroxide are readilyavailable' at low cost and are preferably used.

To obtain the elevated temperatures sometimes necessary in the reaction,elevated pressure may be used. However, with most reactants atmosphericpressure is suflicient. Vacuum may be used when isolating the productsuch as when stripping the solvent. The product can be isolated by othermeans as well, such as by extraction with organic solvents. Thereactions can be conducted either in the presence of air or under aninert atmosphere such as nitrogen. Good results are obtained by eithermethod.

The following examples, in which all parts are by weight, illustrate thecompounds of this invention and their preparation according to themethod outlined above.

EPMMPLE 1 To a reaction vessel equipped with stirring means, heatingmeans, temperature measuring means, reactant introducing means, gasinlet and outlet tubes and a nitrogen source were added a mixture of 139parts of ethylene glycol and 1.4 parts of potassium hydroxide'. Themixture was stirred and the reaction vessel was flushed with nitrogen.To this mixture was added 10.4 parts of paraformaldehyde followed by51.5 parts of 2,6-di-tert-butylphenol.

The mixture was heated with stirring at 35-40 C. for /2 hour, afterwhich it was heated to 70-75 C. and stirred at that temperature for 4hours. The temperature was then maintained at 7580 C. without stirringfor 16 hours, after which time the mixture was allowed to cool. Themixture was then acidified with hydrochloric acid and diluted withbenzene. An organic and an inorganic layer were present. The organiclayer was mechanically separated, washed twice with water and dried invacuo. The residue was taken up in n-pentane and upon standing a solidprecipitated. The solid was removed by filtration, triturated with hotiso-octane, filtered and dried to give white, solid bis(3,5 di tertbutyl-4-hydroxybenzyloxy) ethane, M.P. 147-9 C. Analysis: Calculated for77.1 percent carbon; 10.1 percent hydrogen. Found: 76.8 percent carbon;10.1 percent hydrogen. Infrared spectrum supported the structure.

In the above reaction, the n-pentane mother liquor was allowed to standafter filtration of the bis(3,5-di-tert-butyl-4-hydroxybenzyloxy)ethane. Additional solids precipitated which werefiltered and recrystallized from n-pentane to give a crystalline solid,3,5-di-tert-butyl-4-hydroxybenzylhydroxyethane, M.P. 79-80 C. Calculatedfor C H O 72.8 percent carbon, 10.6 percent hydrogen. Found: 73.0percent carbon, 10.2 percent hydrogen. Infrared spectrum supported thestructure.

Good results are' also obtained when other phenols are reacted withpolyhydric alcohols in the above manner. Thus,2-tert-butyl-6-methylphenol can be reacted with formaldehyde andethylene glycol to yield bis(3-tert-butyl-4-hydroxy-5-methylbenzyloxy)ethane. Likewise, 2,6-diisopropylphenol canbe reacted with formaldehyde and ethyle'ne glycol in the above manner toproduce bis(4-hydroxy- 3,5 diisopropylbenzyloxy)ethane. Also 2 tertbutyl- S-methylphen-ol can be reacted with formaldehyde andmonothioethylene glycol to produce (3-tert-butyl-4-hy droxy 5methylbenzylthio) (3 tert butyl 4 hydroxy 5 methylbenzyloxy)ethane.Further, monothioethylene glycol can be reacted with2-sec-butyl-6-methylphenol and formaldehyde to produce(3-sec-butyl-4-hydroxy 5 methylbenzyloxy) (3 sec butyl 4hydroxy-5-methylbenzylthio)ethane. The above procedure can also be usedto prepare bis[ 3-n-heptyl-4-hydroxy-S-(3- undecyl)benzyloxy]ethane fromthe reaction of ethylene glycol, formaldehyde and2-n-heptyl-6-(3-undecyl)phenol.

EXAMPLE 2 In a pressure vessel equipped with heating means, stirringmeans and temperature measuring means are placed 240 parts of2-tert-amyl-6-(2-nonyl)phenol, 60 parts of paraformaldehyde, 24 parts ofsodium hydroxide and 78 parts of monothioethylene glycol. The pressurevessel is sealed, the mixture is heated to 200 C. and stirred at thattemperature for 4 hours after which time it is allowed to cool. Themixture is acidified with hydrochloric acid and diluted with benzene. Anorganic and inorganic layer are present. The organic layer ismechanically separated, washed with water, and dried in vacuo. Theresidue is taken up in n-hexane and upon standing a solid precipitates.This solid is removed by filtration and dried to yield 3 tert amyl 4hydroxy 5 (2 nonyl)benzylthiohydroxyethane.

Good results are also obtained when other phenols are reacted withpolyhydric alcohols as above. For example, 2-(3-dodecyl)6-n-octylphenolcan be reacted with monothioethyle'ne glycol and formaldehyde to produce3-(3- dodecyl) 4 hydroxy-5-n-octylbenzylthiohydroxyethane. Likewise,2-benzyl-6-methylphenol can be reacted with formaldehyde andmonothioethylene glycol to prepare 3 benzyl 2 hydroxy 5methylbenzylthiohydroxyethane. Further, 2-benzyl-fi-cyclohexylphenol canbe reacted with formaldehyde and 1,6 dimercapto 2,4-dihydroxy-n-hexaneto prepare 1,6-bis(3-benzyl-S-cyclohexyl- 2 hydroxybenzylthio) 2,4dihydroxy-n-hexane. Similarly, 1,2,5 trimercapto 4 hydroxy-n-pentane canbe reacted with formaldehyde and 2-(2-hexyl)-6-(1-naphthyl)phenol toproduce 1,2,5-tris[3-(2-hexyl)-4-hydroxy-(l-naphthyDbenzylthio]-4-hydroxy-n-pentane. Also 1- hydroxy 2,2dihydroxymethyl-n-butane can be reacted with formaldehyde and 2-(a,otdiethylbenzyl)-6-n-octylphenol to prepare 1 [3-(a,udiethylbenzyl)-2-hydroxymethyl-5-n-octylb enzyloxy]-2,2-dihydroxy-n-butane.

EXAMPLE 3 To a reaction vessel equipped with stirring means, heatingmeans, temperature measuring means, reactant introducing means, gasinlet and outlet tubes and a nitrogen source is added a mixture of 200parts of monothioethylene glycol and 34.6 parts of calcium hydroxide.The mixture is stirred and the reaction vessel is flushed with nitrogen.To this mixture is added 60 parts of formaldehyde followed by 346 partsof 2-(4-dodecyl)-6-n-hexylphenol. The mixture is heated with stirring to70 C. and stirred at that temperature for 48 hours, after which it isallowed to cool. The mixture is acidified with hydrochloric acid anddiluted with toluene. An organic and an inorganic layer are present. Theorganic layer is mechanically separated, washed twice with water anddried in vacuo. The residue is taken up in n-pentane and upon standing asolid precipitates. The solid is removed by filtration to give 3(4-dodecyl)-5-n-hexyl-4-hydroxybenzyloxymercaptoethane.

Good results are also obtained when other phenols are reacted withpolyhydric alcohols as above. For example, monothioethylene glycol canbe reacted with formaldehyde and 2 (u ethyl a methylbenzyl) 6 (2undecyl)phenol to prepare 3-(a-ethyl-a-methylbenzyl)-2-hydroxy-5(2-undecyl)benzyloxymercaptoethane. Similarly,Z-(u-methylbenzyl)-6-n-butylphenol can be reacted with formaldehyde andl,4-dihydroxy-2-hydroxymethyl- 3-mercaptomethyl-n-butane to prepare 1,4bis[3 (amethylbenzyl)-5-n-butyl-2 hydroxybenzyloxy] 2hydroxymethyl-3-mercaptomethyl n butane. Also,l-hydroxy-G-mercapto-n-hexane can be reacted with formaldehyde and2-cyc1ooctyl 6 n-heptylphenol to yield 1-(3-cyclooctyl-5-n-heptyl-2-hydroxybenzyloxy) 6 mercapto-n-hexane.

EXAMPLE 4 In a reaction vessel equipped with heating means, stirringmeans and temperature measuring means are placed 412 parts of2,6-di-tert-butylphenol, 120 parts of paraformaldehyde, 20.6 parts oflithium hydroxide and 620 parts of ethylene glycol. The mixture isheated to 260 C. and stirred at that temperature for /2 hour after whichtime it is allowed to cool. The mixture is acidified with hydrochloricacid and diluted with benzene. An organic and an inorganic layer arepresent. The organic layer is mechanically separated, washed with waterand dried in vacuo. The residue is taken up in iso-octane and cooledbelow room temperature during which a solid precipitates. This solid isremoved by filtration and dried to yield 3,5 di tertbutyl-4-hydroxybenzyloxyhydroxyethane.

Good results are also obtained when other phenols are reacted withpolyhydric alcohols in the above manner. For example,Z-tert-butyl-6-methylphenol can be reacted with ethylene glycol andformaldehyde to yield 3-tertbutyl 4 hydroxyl 5methylbenzyloxyhydroxyethane. Also, 2,6-diisopropylphenol can be reactedwith formaldehyde and ethylene glycol to yield4-hydroxy-3,5-diisopropylbenzyloxy hydroxyethane. Similarly, 2, 6ditert-butylphenol can be reacted with 1,2-dimercaptoethane andformaldehyde to yield3,5-di-tert-butyl-4-hydroxybenzylthiomercaptoethane. Further, 2,6dicyclopentyL phenol can be reacted with ethylene glycol to yield 3,5-dicyclopentyl-2-hydroxybenzyloxyhydroxyethane.

8 EXAMPLE 5 In a reaction vessel equipped with stirring means, heatingand cooling means, temperature measuring means, reactant introducingmeans, gas inlet and outlet tubes and a nitrogen source are added amixture of 94 parts 1,2-dimercaptoethane and 82.4 parts of magnesiumhydroxide. The mixture is stirred and the reaction vessel is flushedwith nitrogen. To this mixture is added 60 parts of formaldehydefollowed by 412 parts of 2,6-di-tert-butylphenol. The mixture ismaintained at 20 C. for 2 weeks with stirring. It is then acidified withhydrochloric acid and diluted with benzene. An organic and an inorganiclayer are present. The organic layer is mechanically separated, washedwith water and dried in vacuo. The residue is taken up in n-hexane andcooled below room temperature whereupon a solid precipitates. The solidis removed by filtration to givebis(3,S-di-tert-butyl-4-hydroxybenzylthio ethane.

The above procedure can be used to prepare other compounds from thereaction of a polyhydric alcohol, phenol and formaldehyde. For example,ethylene glycol can be similarly reacted with formaldehyde and2-p-ethylphenyl-6-n-propylphenol to yield bis(4 hydroxy 3 pethylphenyl 5n propylbenzyloxy)ethane. Likewise, 1, 3-dihydroxy 2 mercaptomethyl npropane can be reacted with formaldehyde and 2,6-dibenzylphenol to yield1,3 bis(3,5 dibenzyl 4 hydroxybenzyloxy-Z-(3,5-dibenzyl 4hydroxybenzylthio) 2 (3,5-dibenzyl-4-hydroxybenzylthiomethyl)-n-propane.Also, 1,3-dihydroxyn-propane can be reacted with formaldehyde and2-p-namylphenyl 6 p n nonylphenylphenol to yield 1,3- bis( 3 p namylphenyl-S-p-n-nonylphenyl-4-hydroxybenzyloxy)-n-propane. Similarly,1,3-dihydroxy 2,2-dihydroxymethyl n propane can be reacted with2,6-dip-n-hexylphenylphenol and formaldehyde to yield 1,3- bis(3,5-di-p-n-hexylphenyl 4 hydroxybenzyloxyl-2,2- bis(3,5-di-p-n-hexylphenyl4-hydroxybenzyloxymethyl)- n-propane. Further,1,2,3-trimercapto-5-hydroxy-n-pentane can be reacted with formaldehydeand 2-(a,u-dimethylbenzyl-6-n-decylphenol to prepare 1,2,3-tris[3-(a, adimethylbenzyl) 5 n decyl-4-hydroxybenzylthio]-5-[3-(a,a-dimethylbenzyl)-5-n-decyl 4 hydroxybenzyloxy]-n-pentane. Also,l,2,3,4 tetramercapto-n-butane can be reacted with2-p-methylphenyl-6-n-p-nonylbenzylphenol and formaldehyde to yield1,2,3,4-tetrakis(4- hydroxy-3-p-methylphenyl-S-n-nonylbenzythio) nbutane.

EXAMPLE 6- In a reaction vessel equipped with heating means, stirringmeans and temperature measuring means are added a mixture of 204 partsof 2-cyclohexyl-6-ethylphenol, 30 parts of paraformaldehyde, 10.2 partsof potassium hydroxide and 600 parts of 1,2-dimercaptoethane. Themixture is heated to C. and stirred at that temperature for 8 hoursafter which it is allowed to cool. The mixture is acidified withhydrochloric acid and diluted with toluene. An organic and an inorganiclayer are present. The organic layer is mechanically separated, washedwith water and dried in vacuo. The residue is taken up in n-pentane andupon standing a solid precipitates. The solid is removed by filtrationto give his- (3 -cyclohexyl-5-ethyl-4-hydroxybenzylthio ethane.

Good results are also obtained when other phenols are reacted withpolyhydric alcohols as above. For example,1,2,3-trihydroxy-4-mercapto-n-butane can be reacted with 2-(p-ethylbenzyl)-6-(p-n-propylbenzyl)phenol and formaldehyde to yield1,2,3-tris[3-(p-ethylbenzyl)-4-hydroxy- 5 (p n propylbenzyl)benzyloxy] 4-[3 (p ethylbenzyl) 4 hydroxy 5 -(p n propylbenzyl)benzylthio]-n-butane.Likewise 1,2,3-trihydroxypropane can be reacted with formaldehyde and2,6-di-n-dodecylphenol to give 1,2,3-tris(3,5 di n dodecyl 2hydroxybenzyloxy)-n-propane. Similarly, 2-n-amyl-G-cycloheptylphenol canbe reacted with formaldehyde and 1-hydroxy-4-mercaptobutane to prepare 1(3- n amyl cycloheptyl- 2 hydroxybenzyloxy) 4 (3 n amyl 5 cycloheptyl-2-hydroxybenzylthio)butane. Further, 1,2,3-trimercapton-propane can bereacted with formaldehyde and 2,6-dicyclooctylphenol to yield1,2,3-tris(3,5-dicyclooctyl-2-hydroxybenzylthio)-n-propane. In similarmanner, 1,2-bis- (3 m n heptylphenyl 4 hydroxy 5 o noctylphenylbenzyloxy)-n-propane can be prepared from the reaction offormaldehyde, 1,2-dihydroxy-n-propane andZ-m-n-heptylphenyl-6-o-n-octylphenylphenol.

The compounds of this invention have many important advantages overapparently similar compounds. In the first place they are highlyeffective antioxidants. Secondly, they are compatible with a widevariety of organic media. Thirdly, they are non-staining andnon-discoloring; that is, the use of these compounds as antioxidants donot impart to the medium in which they are used any discoloration orstaining resulting from either the oxidized form of the compound or thereaction product of the oxidized form and the media. This latter problemof discoloration and staining has plagued industries such as the rubberindustry and plastics industry for many years. While many compounds areeffective antioxidants, discoloration and staining attendant with theiruse precludes their commercial acceptance in many areas where the finalproduct must possess defined coloring.

A further property of applicants compounds and a most important one isthe fact that they possess low volatility. In formulating organiccompositions, for example in the rubber and plastics industries as wellas in the food industry, the medium to be protected is subjected toextremes of temperature and pressure such as vulcanizing of rubber,extrusion of plastics and cooking of cereals. Often the oxidation to beprotected against occurs during the processing. Accordingly, anantioxidant to be effectively used must not be lost under theseconditions. Volatility of the additive plays a major part in suchutility. Applicants compounds, which have a low volatility, areperfectly suited for such applications.

Thus applicant has solved not just one problem but a three-fold problem.I have provided not only an antioxidant but one which is non-discoloringand non-staining and also has low volatility. A particular industryWhere all three properties are absolutely critical is the rubberindustry. In the vulcanization of rubber the additive must be addedduring the vulcanization process to protect the rubber from unwantedoxidation. Thus, the compound must not only possess high antioxidantcapability but low volatility is crucial so as to retain the antioxidantin the final product. Further, compounds which are antioxidants and havelow volatility are useless if they discolor or stain. Applicantscompound, as noted above, do s not discolor and does not stain.Accordingly, applicants compounds have achieved a balance of propertieswhich are indeed unique in the antioxidant area.

As noted above, the compounds of this invention are outstandingantioxidants. Therefore, an embodiment of this invention is a newcomposition of matter which comprises organic material normally tendingto undergo oxidative deterioration in the presence of air, oxygen orozone containing an appropriate quantityfrom 0.001 up to about 5percent, and preferably from about 0.10 to about 2 percentof a compoundof this invention.

The compounds of this invention find important utility as antioxidantsin a wide variety of oxygen-sensitive material. Thus liquid hydrocarbonfuels such as gasoline, kerosene and fuel oil are found to possessincreased storage stability by the use of a compound of this invention.Likewise, liquid hydrocarbon fuels such as gasoline which containorganometallic additives such as tetraethyllead as well as otherorganometallic compounds which are used as fuel additives attainappreciably increased oxidative stability by the practice of thisinvention. In addition, lubricant oils and functional fluids, both thosederived from naturally occurring hydrocarbons and those syntheticallyprepared are greatly enhanced by the practice of this invention. Theaddition of small quantities of the compounds of this invention to suchmaterials as turbine, hydraulic, transformer and other highly refinedindustrial oils, soaps and greases; plastics; synthetic polymers such aspolyethylene and polypropylene; organometallic compositions where suchfluids contain tetraethyllead and tetraethyllead antiknock mixtures aswell as other organometallics; elastomers, including natural rubber;lubricating greases; crankcase lubricating oils; and the like, greatlyincrease resistance to deterioration in the presence of air, oxygen orozone.

The compounds of this invention are also very useful in protectingpetroleum wax-parafl5n and microcrystalline wax-against oxidativedeterioration. They also find use in the stabilization of edible fatsand oils of animal and vegetable origin which tend to become rancid,especially during long periods of storage because of oxidativedeterioration. Typical representatives of these edible fats and oils arelinseed oil, cod liver oil, castor oil, soy bean oil, rape seed oil,coconut oil, olive oil, palm oil, corn oil, sesame oil, peanut oil,babassu oil, butter fat, lard, beef tallow, and the like.

The compounds of this invention are very effective antioxidants for highmolecular weight unsaturated hydrocarbon polymers, such aspolybutadiene, methyl rubber, polybutene rubber, natural rubber, butylrubber, GR-S rubber, GR-N rubber, piperylene rubber, dimethyl butadienerubber and the like. Thus a preferred embodiment of the presentinvention is a rubber containing as an antioxidant therefor, a compoundof this invention as defined above. Another part of this invention isthe method of preserving rubber which comprises incorporating therein acompound of this invention as defined above. The stabilizer isincorporated into the rubber by milling, Banbury mixing, or similarprocess, or is emulsified and the emulsions added to the rubber latexbefore coagulation. In the various embodiments of this invention thestabilizer is used in small amounts, generally ranging from about 0.001to about 5 percent, based on the rubber.

As used in the description and claims, the term rubher is employed in ageneric sense to define a high molecular weight plastic material whichpossesses high extensibility under load coupled with the property offorcibly retracting to approximately its original size and shape afterthe load is removed. It is preferable that the rubber be asulfur-vulcanizable rubber, such as India rubber, reclaimed rubber,balata, gutta percha, rubbery conjugated diene polymers and copolymersexemplified by the butadiene-styrene (GR-S) and butadiene-acrylonitrile(GR-N or Paracril) rubbers and the like, although the invention isapplicable to the stabilization of any rubber, high molecular weightorganic material which is normally susceptible to deterioration in thepresence of oxygen, air, or ozone. The nature of these rubbers is wellknown to those skilled in the art.

Among the definite advantages provided by this invention is that thepresent rubber compositions possess unusually great resistance againstoxidative deterioration. Moreover, these compositions exhibit excellentnon-staining and non-discoloration characteristics. Furthermore, thestabilizers are relatively inexpensive and easily prepared, and possessthe highly beneficial property of low volatility. As noted above, ahighly desirable feature of a rubber antioxidant is that it has a lowvolatility so that it remains admixed with the rubber duringvulcanization and related processsteps. Q

The present invention will be still further apparent from the followingspecific examples wherein all parts and percentages are by weight.

of 60,000, 50 parts of mixed zinc propionate-stearate, 50 parts ofcarbon black, 5 parts of road tar, 2 parts of sul- EXAMPLE 9 Two partsof S-tert-butyl 4 hydroxy-S-methylbenzyloxyhydroxyethane areincorporated in 100 parts of raw butyl rubber prepared by thecopolymerization of 90 percent of isobutylene and 10 percent ofisoprene.

EXAMPLE 10 To 200 parts of raw butyl rubber prepared by copolymerizationof 95 percent of isobutylene and percent of butadiene is added 5.0 partsof bis(3-tert-butyl-4-hydroxy-S-methylb enzyloxy) ethane.

EXAMPLE 1 1 To a master batch of GR-N synthetic rub-ber'comprising 100parts of GR-N rubber, 5 percent of zinc stearate, 50 parts of carbonblack, 5 parts of road tar, 2 parts of sulfur and 2 parts ofmercaptobenzothiazole is added 2.0 percent based on the weight of thebatch of 4-hydroxy- 3,5-diisopropylbenzyloxy hydroxyethane.

EXAMPLE 12 To natural rubber (Hevea) is added 0.10 percent ofbis(4-hydroxy-3,S-diisopropylbenzyloxy)ethane.

EXAMPLE 13 Natural rubber stock is compounded according to the followingformula:

Parts Thick gristly crepe natural rubber 100 Wax 2 Ultramarine dye 0.1Zinc oxide 70 Titanium dioxide 20 Sulfur 3 Stearic acid 1.23,5-di-tert-butyl-4-hydroxybenzylthiomercaptoethane 4 Benzothiazyldisulfide 0.4 Amine activator 0.5

This stock is then vulcanized for 60 minutes at 280 F.

EXAMPLE 14 A butadiene-acrylonitrile copolymer is produced frombutadiene-1,3 and 32 percent of acrylonitrile. Two percent (based on thedry weight of the copolymer) of bis (3-tert-butyl 4 hydroxy 5methylbenzylthio)ethane is added as an emulsion in sodium oleatesolution to the latex obtained from emulsion copolymerization of themonomers. The latex is coagulated with a pure grade of aluminum sulfateand the coagulum, after washing, is dried for 20 hours at 70 C.

EXAMPLE 15 Three-percent of3-tert-amyl-4-hydroxy-5-(2-nonyl)benzylthiohydroxyethane emulsified insodium oleate is added to a rubber-like, copolymer of butadiene-l,3 andstyrene containing 25 percent of combined styrene.

EXAMPLE 16 A rubber stock is compounded from 100 parts of smoked sheetrubber, 60 parts of zinc oxide, 20 parts of lithopone, 2 parts ofsulfur, 0.7 part of diphenyl guani- 12 dine phthalate, 0.8 part ofbenzoyl thiobenzothiazole, 0.2 part of paraffin and 0.001 part of1,2,3,4-tetrakis(4-hydroxy-3-pmethylphenyl-5-n-nonylbenzylthio)-n-butane. The stock so compounded iscured by heating for 45 minutes at 126 C. in a press.

Each of the above illustrative rubber compositions of this inventionpossesses greatly improved resistance against oxidative deterioration ascompared with the corresponding rubber compositions which are devoid ofan antioxidant. Moreover, the light-colored stocks of the above examplesexhibit virtually no discoloration or staining characteristics even whensubjected to severe Weathering conditions and the like. The methods offormulating the improved rubber compositions of this invention will nowbe clearly apparent to those skilled in the art.

To illustrate the enhanced oxygen resistance of the rubber compositionsof this invention and the excellent non-staining and non-discolorationcharacteristics of the compounds of this invention a light colored stockis selected for test. This stock has the following composition.

To the above base formula is added one part by weight ofbis(3,5-di-tert-butyl 4 hydroxybenzyloxy) ethane and individual samplesare cured for 20, 30, 45 and 60 minutes at 274 C. using perfectly cleanmolds with no mold lubricant. Another set of samples of the same baseformula which does not contain an antioxidant is cured under the sameconditions.

To demonstrate the protection afforded to the rubber bybis(3,S-di-tert-butyl-4-hydroxybenzyloxy)ethane and to contrast the samewith inhibitor-free stocks, the tensile strength and the ultimateelongation of the test specimens are determined before and after aging.The aging is accomplished by conducting the procedure of ASTMDesignation: D-572-52, describedin the ASTM Standards for 1952, part 6,for a period of 168 hours at a temperature of C. with an initial oxygenpressure in the test bomb of 300 p.s.i.

The tensile strength and the ultimate elongated of the test specimensbefore and after aging are measured by ASTM Test Procedure, D-4125 1T(ASTM Standards for 1952, part 6). The tensile strength is the tensionload per unit cross-sectional area required to break a test specimen,while the ultimate elongation is the elongation at the moment of ruptureof a test specimen. A decrease in the values of either of theseproperties upon aging represents a decrease in the usefulness of thearticle fabricated therefrom, so that the degree to which theseproperties are retained is a direct measure of the utility of theprotective substance.

Measurements are also made of the increase in weight of the testspecimens which occurred during the accelerated aging. This is a directmeasure of the oxygen uptake of the samples and provides an othercriterion of the effectiveness of an inhibitor in suppressing oxidativedeterioration of the rubber. Thus, the larger the weight increase, thegreater is the deterioration and the less effective is the inhibitor.

The results of these tests show thatbis(3,5-di-tertbutyl-4-hydroxybenzoyloxy)ethane is a superior rubberantioxidant.

Furthermore, on exposure to ultraviolet light in the weatherometer, itis noted that the typical composition of this invention possessesessentially no discoloration.

The amount of inhibitor employed in the rubber compositions of thisinvention varies from about 0.001 to about percent by weight based onthe weight of the rubber. The amount used depends somewhat upon thenature of the rubber being protected and the conditions of service to beencountered. Thus, in the stabilization of natural and synthetic rubberto be used in the manufacture of tires which are normally subjected toexposure to the elements, as well as to the action of sunlight,frictional heat, stress, and the like, the use of relatively highconcentrations of this inhibitor is advantageous. On the other hand,when the article of manufacture is not to be subjected to such severeconditions, relatively low concentrations can be successfully utilized.Generally speaking, amounts ranging from about 0.1 to about 2 percent byweight give uniformly satisfactory results.

Other rubbers and elastomerswhich can be preserved according to thisinvention are the rubbery polymerizates of isoprene, butadiene-1,3,piperylene; also the rubber co-polymer of conjugated dienes with one ormore polymerizable monoolefinic compounds which have the capability offorming rubbery co-polymers with butadiene-1,3, outstanding examples ofsuch monoolefinic compounds being those having the group CH C,exemplified by styrene. Examples of such monoolefins are styrene, vinylnaphthalene, alpha methyl styrene, para-chlorostyrene, dichlorostyrene,acrylic acid, methyl acrylate, methyl methacrylate, methacrylonitrile,methacrylamide, methyl vinyl ether, methyl vinyl ketone, vinylidinechloride, vinyl carbazole, vinyl pyridines, alkyl-substituted vinylpyridines, etc. In fact, excellent stabilization is achieved byincorporating a compound of this invention in any of the well-knownelastomers which are normally susceptible to deterioration in thepresence of air, such as elastoprenes, elastolenes, elastothiomers, andelastoplastics.

The compounds of this invention are also useful in preventing oxidativedeterioration in lubricating oil composition. Thus, an embodiment ofthis invention is a lubricating oil normally susceptible to oxidativedeterioration and a small antioxidant quantity, up to 5 percent, of acompound of this invention as defined above.

To prepare the lubricants of this invention an,appropriate quantityfromabout 0.001 to about 5 percent and preferably from about 0.10 to about 2percent-of a compound of this invention is blended with the base oil tobe protected. Suitable base oils include mineral oils and also syntheticdiester oils such as sebacates, adipates, etc., which find particularuse as aircraft instrument oils, hydraulic and damping fiuids andprecision bearing lubricants. All of these base oils are normallysusceptible to oxidative deterioration, especially at elevatedtemperatures. The finished lubricants of this invention have muchgreater oxidation stability and many other improved performancecharacteristics as compared with the corresponding base oils.

To illustrate the useful antioxidant properties of the novel products ofthis invention, polyveriform oxidation stability tests were conducted.The polyveriform oxidation test is described in the paper entitled,Factors Causing Lubricating Oil Deterioration in Engines, Ind. and Eng.Chem., Anal. Ed., 17, 302 (1945). See also, A Bearing Corrosion Test forLubricating Oils and Its Correlation With Engine Performance, Anal.Chem., 21, 737 (1949). This test effectively evaluates the performanceof lubricating oil antioxidants. The test equipment procedure employedand correlations of the results with engine performance are discussed inthe first paper above cited. By employing various products of thisinvention in oxygen-sensitive lubricating oil, effective inhibition ofoxidative deterioration is achieved.

The comparative tests were conducted using the method and apparatusessentially as described in the publication first above mentioned. Oneminor modification was that the steel sleeve and copper test piecedescribed in this publication were omitted from the apparatus. In thesetests an initially additive-free, V.I. solvent-refined SAE-lO crankcaseoil was used. The principal conditions consisted of passing 48 liters ofair per hour through the test oil for a total period of 20 hours whilemaintaining the oil at a temperature of 300 C. Oxidative deteriorationof the oil was further promated by employing as oxidation catalysts 0.05percent by weight of ferric oxide (as ferric Z-ethylhexoate) and 0 .10percent by weight of lead bromide, both of these amounts being basedupon the weight of oil employed. Lubricating oils were prepared byblending individual portions of the above lubricating oil with 1 percentby weight of bis(3,5- di-tert-butyl-4-hydroxybenzyloxyethane and 1percent by weight of 3,5 di-tert-butyl-4-hydroxybenzyloxyhydroxyethane.These composition were then subjected to the above stringent oxidationtest. In addition to the foregoing examples an additional test specimenwas formulated consisting of the additive-free crankcase oil describedabove and one weight percent of 2,6-di-tert-butyla-methoxy-p-eresol.This compound is quite similar to applicants compound in that on the onehand the first compound named above is essentially a dimer of thiscompound. The second compound named above differs only by the presenceof a hydroxyl group. These differences, as will be noted in the results,turn out to be quite critical. Thus the similarity between applicantscompounds and 2,6-di-tert-butyl-u-methoxy-p-cresol is only one ofstructure and not of affect. The results of these tests are shown inTable I.

TABLE I.EFFEOT OF PRODUCTS OF THIS INVENTION ON THE OXIDATION OFLUBRICATING OIL By referring to the data presented in Table I, it isimmediately apparent that the products of this invention effectivelyinhibit the oxidative deterioration of lubricating oil. While2,6-di-tert-butyl-a-methoxy-p-cresol does effectively lower the percentviscosity increase of the test oil, it only does so by 32 percent,whereas applicants compounds lower the viscosity increase by 58 and 65percent. Thus applicants compounds are almost two times as effective asa very similar compound. This similar compound is a commercialantioxidant itself and is the subject of US. Patent No. 2,838,571granted to applicants assignee. This result is even more startling whenit is considered that the test was conducted on a weight percentagebasis. There are substantially as many phenolic groups in the testsamples containing applicants compounds as in the test sample containingthe compared compound.

The following examples illustrate lubricating oil compositions of thisinvention.

EXAMPLE 17 To 1,000 parts of a solvent refined neutral oil 95 V.I. and200 SUS at F. containing 6 percent of a commercial methacrylate Type VIapprover which gives the finished formulation of a V.I. of and aviscosity of 300 SUS at 100 F. is added 5 percent of 1-[3-(a,a-diethylbenzyl) 2 hydroxy 5 n-octylbenzyloxy]-2,2-dihydroxy-n-butane.

EXAMPLE 18 To an additive-free solvent refined crankcase lubricating oilhaving a viscosity index of 95 and an SAE visocity of 10 is added 0.001percent of 3-(a-ethyl-u-methylbenzyl)- 2-hydroxy-5- (Z-undecylbenzyloxymercaptoethane.

15 EXAMPLE 19 To 100,000 parts of a petroleum hydrocarbon oil having agravity of 30.3 API at 60 F., a viscosity of 178.8 SUS at 100 F., aviscosity index of 154.2 and which contains 0.2 percent sulfur, is added200 parts of bis(4 hydroxy 3 p-ethylphenyl--n-propylbenzyloxy) ethane.The resulting oil possesses greatly enhanced resistance to oxidativedeterioration.

EXAMPLE 20 To 100,000 parts of a commercially available pentaerythritolester having a viscosity at 100 F. of 22.4 centistokes, and known in thetrade as Hercoflex 600 is added 400 parts (0.4 percent) ofbis(3-cyclohexyl-5- ethyl-4-hydroxybenzylthio)ethane. The resultingfinished oil possesses markedly improved resistance against oxidativedeterioration.

EXAMPLE 21 To 100,000 parts of dioctyl sebacate having a viscosity of210 F. of 36.7 SUS, a viscosity index of 159' and a molecular weight of426.7 is added 250 parts (0.25 percent) of3-benzyl-Z-hydroxy-5-methylbenzylthiohydroxyethane.

The products of this invention are also useful as aditives tives tofunctional fluids and automatic transmission fluids. The primaryconstituent of a functional fluid is a refined mineral lubricating oilhaving a carefully selected minimum viscosity of 49 Saybolt Universalseconds (SUS) at 210 F. and a maximum viscosity of 7,000 -SUS at 0 F.,generally a distillate oil, lighter than an SAE motor oil. The oilusually amounts to between about 73.5 to about 97.5 percent by weight ofthe finished fluid. Preferably, the base oil is selected from a paraffinbase distillate such as a Pennsylvania crude.

The fluids usually contain compounds which are characterized bycontaining one or more organic components which may be alkyl, aryl,alkaryl or aralkyl groups that are bonded to one or more metal atomsthrough coupling groups such as sulfonate, hydroxyl, carboxyl andmercaptan. The metal atoms may be aluminum, calcium, lithium, barium,strontium and magnesium. The organic components contain oil solubilizinggroups such as high molecular weight straight or branched chainparaflins, aromatic or naphthenic rings, or contain a halogen. Thesemetal compounds are present in the compounded fluid in a concentrationrange of between about 0.1 to about 5 percent by weight. These compoundsinclude alkaline earth metal salts or phenyl-substituted long chainfatty acids, alkaline earth metal salts of the capryl or octyl esters ofsalicylic acid, the alkaline earth metal salts of petroleum sulfonicacids, the alkaline earth metal salts of alkyl-substituted phenolsulfides, the salt of aluminum or the alkaline earth metals with cetylphenol, and the metal salts of wax-substituted phenol derivatives.Another class of additives are the so-called overbased phenates andsulfonates, which can be prepared by reaction between an alkyl phenol oralkyl phenol sulfide and an alkaline earth metal oxide or hydroxide atan elevated temperature. The overbased phenate formed from the reactioncontains up to two or three times as much metal as the normal phenate.

In addition, functional fluids may contain additional components whichimprove the properties of the fluid. Typical components includeanti-Squawk additives, pour point depressants, foam inhibitors, rustpreventatives, extreme pressure agents, metal deactivators and viscosityindex improvers.

The following examples show typical functional fluids of this invention.The fluids are formed by mixing the ingredients together, while heatingthe oil to a temperature up to 200 F.

EXAMPLE 22 A fluid of this invention is prepared by blending 80 parts ofa conventionally-refined Pennsylvania mineral 16 oil (99 SUS at 100 F.)2 parts 1,2-bis(3-m-n-heptylphenyl 4 hydroxy 5o-n-octylphenylbenzyloxy)-npropane, 5 parts of barium petroleumsulfonate, 10 parts of a polyacrylate having a molecular weight ofapproximately 7,000 derived from a fatty alcohol such as cetyl or laurylalcohol, 0.1 part of a dimethyl silicone polymer anti-foam agent, 2parts of a dialkyl zinc dithiophosphate and 0.9 part of a dark, viscousliquid having a viscosity of 560 SUS at 210 F., a flash point of 4207F., a pour point of 30 F. and a specific gravity of 60/'60 F. of 0.919.

EXAMPLE 23 Another such fluid consists of parts of a solvent refined,light acid-treated, clay-contacted, solvent dewaxed paraflin basedistillate mineral oil (110 SUS at F.); 0.1 part of3-sec-butyl-4-hydroxy-S-methylbenzyloxy-3'-sec-butyl-4'-hydroxy-5'-methylbenzylthioethane; 0.1 part of calciumoctylphenol sulfide; 2 parts of a sulfurized sperm oil having a sulfurcontent between 10-12 percent, a viscosity of 210 F. of 200 SUS and apour point of 65 F., 0.3 part of an ester of an aromatic acid andwax-alkylated phenol having a molecular weight of approximately 450; 2.5parts of a linear pale color isobutylene polymer of a controlledmolecular Weight having a viscosity of 3,000 SUS at 210 F., a specificgravity of 60/60 F. of 0.875.

Liquid hydrocarbon fuels employed in the operation of spark ignitioncombustion engines are also vastly improved in their storage stabilityby the practice of this invention. Table II, below gives thecompositions of a number of typical commercial gasolines which may bestabilized against oxidative deterioration by the inclusion therein of aproduct of this invention.

TABLE IL-GASOLINE COMPOSITIONS Percent Percent Percent Gravity, GasolineAromatics Olefins saturates API EXAMPLE 24 To 1,000 parts of Gasoline A,as described in Table II, is added 10 parts of3(4-dodecyl)-5-n-hexyl-4-hydroxybenzyloxymercaptoethane.

EXAMPLE 25 To 10,000 parts of Gasoline B is added 50 parts of bis-[3-n-heptyl-4-hydroxy-5-(3-undecyl)benzyloxy]ethane.

EXAMPLE 26 To 500 parts of Gasoline C, as described in Table II, isadded 10 parts of 1-(3-cyclooctyl-S-n-heptyl-Z-hydroxybenzyloxy)-6-mercapto -n-hexane.

EXAMPLE 27 To 2,000 parts of Gasoline D is added 15 parts of 1,2,3-tris[3 (a,a-dimethylbenzyl)-S-n-decyl-4-hydroxybenzylthio] 5[3-(u,a-dimethylbenzyl)-5-n decyl-4-hydroxybenzyloxy1-n-pentane.

EXAMPLE 28 To 10,000 parts of Gasoline E is added 500 parts of1,3-bis(3-p-n-amylphenyl 5 p-nonylphenyll hydroxybenzyloxy)-n-propane.

Antiknock compositions and spark ignition internal combustion enginefuels containing mixtures of organolead antiknock agents andcyclopentadienyl manganese tricarbonyls are also vastly improved intheir storage stability by the practice of this invention. Suchcompositions are described more fully in U.S. Pat. No. 2,818,417.

Despite their great general stability cyclopentadienyl manganesetricarbonyls accelerate and in some cases cause deterioration of leadedgasolines containing them. Research has shown that cyclopentadienylmanganese tricarbonyls serve as deterioration catalysts but the mannerby which they exert this adverse effect cannot presently be explained.All available evidence indicates that the manganese compounds catalyzethe simultaneous deterioration of the organo antiknock agent and thebase fuel. This results in the premature formation of organoleaddecomposition products (both soluble and insoluble) and gum and othersludges resulting primarily from the fuel deterioration. In addition,the amounts of these decomposition products are ultimately increased.Hence, the problem is a combination of increased rate of deteriorationand increased extent of deterioration.

The problem is not merely the conventional one of providing protectionagainst the oxidative deterioration of clear gasolines or of leadedgasolines. For instance, a number of powerfully effective antioxidantsof proven ability to stabilize clear and leaded gasolines have beenfound to fail completely when used in an attempt to overcome thisproblem. In fact, after much research it has been found that priorconcepts of gasoline and gasoline additive stabilization are of no helpwhatsoever in seeking to find a solution to this complex problem.

As a further illustration of the unique character of this problem, ithas been found that a widely used metal deactivatorN,N'-disalicylidenel,2-diaminopropane affords no relief whatsoever from the presentproblem. In fact, the metal deactivator actually further increases theamount of deterioration that occurs in manganesecontaining leadedgasolines. Hence the present problem is not a simple type of metalcatalyzed oxidative deterioration that can be remedied by conventionalmeans, such as by complexing metallic fragments (produced by initialdecomposition of the metallic additives) by means of a metaldeactivator. It is seen that the present problem is the result of ahighly complex interplay among the various ingredients (and perhapstheir decomposition products) of these commercially important organoleadmanganese compositions.

Leaded gasolines containing a minor amount of a cyclopentadienylmanganese tricarbonyl or cyclopentadienyl nickel nitrosyl can beeffectively stabilized by the presence therein of a small quantity of acompound of this invention, such asbis(3,5-di-tert-butyl-4-hydroxybenzyloxy)ethane. These compounds havebeen found to completely eliminate the problem at hand. In fact, in manycases, the compositions of this invention have stabilities at least asgreat as those of the corresponding manganese and nickel-free leadedgasolines.

In the compositions of this invention the concentrations of the primeingredients will vary. Thus the finished fuels of this invention cancontain from about 0.2 to about 6.4 grams of lead per gallon as anorganolead antiknock agent. The manganese or nickel concentrationstherein can range from about 0.005 to about 6 grams per gallon as acyclopentadienyl manganese tricarbonyl or cyclopentadienyl nickelnitrosyl respectively. On a cost effectiveness basis, finished motorfuels containing per gallon from about 1 to about 4 grams of lead andfrom 0.05 to about 2 grams of manganese or nickel are preferred. In allof these finished fuels the concentration of the above compounds of thisinvention can be from about 0.002 to about 0.01 weight percent based onthe fuel. Expressed in different units these concentrations correspondrespectively to about 0.5 to about 25 pounds per thousand barrels offuel. These concentrations are sufficient to inhibit the deteriorationwhich would occur in the absence of the compounds of this invention.

In formulating finished fuels it is common practice to employconcentrated gasoline solutions of the additives. These stock solutionsare then cut with or metered into the remainder of the gasoline toachieve the appropriate concentration in the finished fuel. A feature ofthis invention is that such concentrated stock solutions are likewisevery effectively stabilized by the presence therein of a compound ofthis invention. Consequently, the concentrations of the aboveingredients can be as much as 10 times as high as those set forth above.The choice of concentrations is within the discretion of the refiner andtakes into consideration the quantities of gasoline being processed, thestorage temperatures to be accounted, the length of storage involved,etc. The specific concentrations given above are for illustrativepurposes only and are not to be considered as limitations upon thisinvention.

Another embodiment of this invention is an antiknock fluid compositionadopted for use as an additive to gasoline, which composition consistsessentially of an organolead antiknock agent, a cyclopentadienylmanganese tricarbonyl or cyclopentadienyl nickel nitrosyl and a compoundof this invention as defined above, there being present in thecomposition from about 0.00078 to about 30 parts of manganese or nickelper part of lead and from about 0.1 to about 5 weight percent of acompound of this invention based on the weight of the organoleadantiknock agent. These compositions possess greater stability by virtueof the presence therein of a compound of this invention. Furthermore,these compositions provide an excellent vehicle by which the finishedfuels of this invention can be formulated.

The foregoing compositions of this invention can also contain otheradditives known in the art. Halogen scavengers for the organoleadantiknock agents (ethylene dibromide and/or ethylene dichloride, etc.),corrective agents (phosphorus, arsenic and antimony compounds, etc.),dyes, solvents and/or diluents are illustrative of the types ofadditives which can be co-present.

To demonstrate the striking improvement resulting from this invention,storage tests are conducted, a number of fuel blends are made up usingtwo commercially available gasolines of widely differing stabilities.Each of these base fuels are treated with tetraethyllead so that theconcentration thereof is 3 ml. per gallon (3.18 gram of lead pergallon). The tetraethyllead is used in the form of commercial motor mix(tetraethyllead, 0.5 theory of ethylene dibromide and 1.0 theory ofethylene dichloride). To portions of each of these fuels is then addedmethylcyclopentadienyl manganese tricarbonyl to a concentration of 0.5gram of manganese per gallon. Samples of these manganese-containingleaded fuels are then treated per this invention with residuel oil No. 3in Table III, a product of this invention. Concentrations equivalent tosix pounds per one thousand barrels are used. For comparative purposes,identical samples are made up containing six pounds per one thousandbarrels of a commercial antioxidant of proven ability and widely used tostabilize gasolines both clear and leaded. This additive is referred tobelow as commercial additive.

The various test fuels are stored at 110 F. and periodically analyzed todetermine their content of gum and soluble alkyl lead salts. The gumcontent is determined by the standard ASTM tests procedure D381. Thesoluble alkyl lead salts are determined by extracting samples of thestored fuels with an ammonia ammonium acetate solution and assaying theamount of lead so extracted. The formation of gum and soluble alkyl leadsalts is, of course, proof that decomposition of the fuel has takenplace. Therefore, the relative stabilities of the test fuels aredirectly measured by determining the length of time required to form 7mg. of gum per ml. of fuel and 3 mg. of lead as soluble alkyl lead saltsper 100 ml. of fuel. The longer the time required to form these amountsof decomposition products the more stable is the fuel composition. Inthis test, fuels of this invention are stable for a substantially longertime than are fuels not containing a product of this invention.

The following examples illustrate the compositions of this invention andthe methods by which they are prepared.

EXAMPLE 29 To 1000 gallons of a commercial gasoline having a gravity of590 API, an initial boiling point of 98 F. and a final boiling point of390 F. are added 3.18 grams per gallons of lead as tetraethyllead, 0.6theory (based on the lead) of bromine as ethylene dibromide, 1.0 theory(based on the lead) of chlorine as ethylene dichloride, 0.25 gram ofmanganese per gallon as methylcyclopentadienyl manganese tricarbonyl and0.0002 Weight percent (based on the gasoline) of1,2,3tris(3,5-dicyclooctyl-2- hydroxybenzylthio)-n-propane. Theresultant fuel possesses enhanced stability characteristics.

EXAMPLE 30 With a gasoline having an initial boiling point of 93 F., afinal boiling point of 378 R, an API Gravity of 562 and a tetraethylleadcontent equivalent to 0.2 gram of lead per gallon are blendedcyclopentadienyl nickel nitrosyl to a concentration of 0.05 gram ofnickel per gallon and 1,3-bis(3,5-dibenzyl-4-hydroxybenzyloxy)-2-(3,5-dibenzyl-4-hydroxybenzylthio) 2(3,5-di'benzyl-4-hydroxybenzylthiomethyl)-n-propane to a concentrationof 0.005 weight percent (based on the gasoline). The finished fuel soformed possesses improved stability properties.

EXAMPLE 31 To a gasoline having an API gravity of 51.5 R, an initialboiling point of 91 F. and a final boiling point of 394 F. are blended6.4 grams of lead per gallon as tetrabutyllead, 2 grams of manganese pergallon as octylcyclopentadienyl manganese tricarbonyl and 0.0008 weightpercent (based on the gasoline) of 1,2,3-tris[3-(pethylbenzyl)-4-hydroxy5 (p-n-propylbenzyl)benzyloxy]-4-[3-p-ethylbenzyl) 4hydroxy-S-(p-n-propylbenzyl)benzylthio]-n butane. The resultant fuelpossesses very good stability.

EXAMPLE 32 With a gasoline having an initial boiling point of 93 F. anda final boiling point of 410 F. are blended 2 grams of lead per gallonas tetraphenyllead, 6 grams of nickel as diethylcyclopentadienyl nickelnitrosyl, 1 theory (based on the lead) of bromine as ethylene dibromideand 0.01 Weight percent (based on the gasoline) of 1,6-bis(3-benzyl-5-cyclohexyl-2-hydroxybenzylthio) 2,4 dihydroxy-n-hexane.The finished fuel has very good storage stability This invention alsoextends to the use in the above compositions of manganese pentacarbonyl(i.e., dimanganese decacarbonyl) Saturated hydrocarbon syntheticpolymers are also greatly enhanced by the practice of this invention.The saturated hydrocarbon synthetic polymers which are greatly enhancedin oxidative stability by the practice of this invention, includespolymers obtained from the polymerization of a hydrocarbon monoolefinhaving up to 4 carbon atoms.

Examples of such monomers include ethylene, propylene, butylene andisobutylene. Thus the polymers are homopolymers and copolymers ofethylene, propylene, butylene and isobutylene.

A preferred embodiment of this invention is polyethylene containing asmall antioxidant quantity, up to about 5 percent, of a product of thisinvention. A particularly preferred embodiment of the inventioncomprises polyethylene containing from about 0.01 to about 2 percent ofa product of this invention. In particular it is found that when from0.01 to about 2 percent ofbis(3,5-di-tertbutyl-4-hydroxybenzyloxy)ethane is incorporated inpolyethylene compositions of outstanding oxidative stability result.This is true, in particular for bis(3,5-di-tert-buty1- 2.04-hydroxybenzyloxy)ethane. Thus bis(3,5-di-tert-butyl-4-hydroxybenzyloxy)ethane represents an especially preferred inhibitor ofthis invention.

Polyethylene is a hydrocarbon polymer derived from the polymerization ofethylene. This polymerization can be accomplished by a great variety ofmethods which lead to .products of diverse properties. Polyethylene ofany nature may advantageously be utilized for preparing compositionsaccording to the present invention. The polymers of ethylene which areemployed may, for example, besimilar to those which may be obtained bypolymerizing ethylene in a basic aqueous medium and in the presence ofpolymerization-favoring quantities of oxygen under. relatively highpressures in excess of 500 to 1,000 atmospheres at temperatures between150 and 275 C. Or, if desired, they may be similar or identical to theessentially linear and unbranched polymers ordinarily having greatermolecular Weights which may be obtained under relatively low pressuresof 1 to atmospheres using such catalysts to polymerize the ethylene asmixtures of strong reducing agents and compounds of Group IVB, V-B andVI-B metals of the Periodic System; chromium oxide and silicatedalumina; hexavalent molybdenum compounds; and charcoal supportednickel-cobalt. The polyethylene which results from these variouspolymerization processes may have a molecular weight in the range from1300 to over 1,000,000 depending on the particular conditions ofpolymerization employed.

The benefits derived from the practice of this invention aredemonstrated by comparative oxidation tests of uninhibited polyethyleneand polyethylene containing an antioxidant of this invention. Thesetests are conducted as follows: The selected amount of antioxidant isblended With the polyethylene by milling a weighed quantity of plasticpellets on a warm roll-mill. The weighed quantity of antioxidant isadded to the mill after the polyethylene has been premilled for a shortperiod of time. The plastic containing the antioxidant is then added inWeighed quantity to a standard size vessel and melted to give a surfaceof reproducible size. The vessel is then inserted into a chamber whichmay be sealed and which is connected to a capillary tube leading to agas buret and leveling bulb. The apparatus is flushed with oxygen atroom temperature, sealed, and the temperature is raised to C. The oxygenpressure is maintained at 1 atmosphere by means of a leveling bulb. Theoxygen uptake at the elevated temperature is recorded until sharpincrease in the oxygen uptake occurs. This procedure has been adoptedsince it has been found that many compounds may inhibit the oxidationfor a certain induction period after which time a very sharp increase inthe rate of oxygen uptake occurs indicating that the antioxidant hasbeen exhausted. In tests of this nature it is found that thecompositions of this invention have greatly increased the inductionperiods.

There are several methods available for preparing the inhibitedhydrocarbon polymer compositions of this invention. Thus, the blendingof the products in this invention with a polymer such as, for example,polyethylene, may be carried out on open rolls, on internal mixers ormay be accomplished by mixing with extrusion. It is also possible toprepare concentrated batches of the polymer containing excessive amountsof the products of this invention and then mix the concentrate withadditional polymer to prepare a composition of this invention. Thepreferred method of compounding the polymers is by milling on heatedopen rolls at slightly elevated temperatures by methods well-known tothe art. The temperature range employed is sometimes critical as certainpolyethylenes will not melt at low temperatures and tend to stick to therolls at high temperatures. The products of this invention may beinitially mixed With the polymer in the dried state or it may be firstdissolved in a suitable solvent, then sprayed on the polymer and milledin.

21 Examples of the hydrocarbon polymer compositions of this inventionprepared as described above follow. All parts and percentages are byweight in these examples.

EXAMPLE 3 3 To 1000 parts of polyethylene produced by oxygen catalizedreaction under a pressure of 20,000 atmospheres and having an averagemolecular weight of 40,000 is added and mixed 2 parts of3-(3-dodecyl)-4-hydroxy-5-n-octylbenzylthiohydroxyethane. The resultingcomposition has greatly increased oxidative stability.

EXAMPLE 34 With 200 parts of polyisobutylene having an average molecularweight of 100,000 is blended 1.0 part bis(3,5-di-tert-butyl-4-hydroxybenzylthio)ethane.

EXAMPLE 35 To a master batch of high molecular weight polyethylenehaving an average molecular weight of about 1,000,- 000, a tensilestrength of 6,700 p.s.i., a Shore D hardness of 74 and a softeningtemperature under low load of 150 C. is added 5 percent of3,5-dicyclopentyl-2-hydroxybenzyloxyhydroxyethane.

EXAMPLE 36 To a polyethylene having an average molecular weight of 1500,a melting point of 88-90 C. and a specific gravity of 0.92 is added 1percent of l,2,3-tris(3,5-di-ndodecyl-2-hydroxybenzyloxy)-n-propane.After milling in the antioxidant an extremely oxidation-resistantproduct results.

EXAMPLE 38 Two parts of3,5-di-tert-butyl-4-hydroxybenzyloxyhydroxyethane are added with millingto 100 parts of a low density polyethylene prepared by high pressurepolymerization and which has an average molecular weight of about20,000. The resulting product is vastly improved in its oxidativestability.

EXAMPLE 39 To 10,000 parts of a polyethylene having an average molecularweight of about 100,000 and which has a tensile strength of 5400 p.s.i.,a Shore D hardness of 70 and a softening temperature of 130 C. under lowload is added 10 parts 1-(3-n-amyl-5-cycloheptyl-Z-hydroxybenzyloxy) 4(3 n amyl 5 cycloheptyl 2 hydroxybenzylthio)butane to prepare acomposition of outstanding oxidative stability.

EXAMPLE 40 To the polyethylene in Example 9 is added 0.05 percent1,3-bis(3,5-di-p-n-hexylpheny1-4-hydroxybenzyloxy)- 2,2 bis( 3,5 di p nhexylphenyl 4 hydroxybenzyloxyrnethyD-n-propane. The resultingcomposition has improved antioxidant characteristics.

EXAMPLE 41 Two parts of 1,2,5-tris[3-(2-hexyl)-4-hydroxy-5-(1-naphthylbenzylthio)-4-hydroxy]-n-pentane are added with milling to 100parts of a low density polyethylene prepared by high pressurepolymerization and which has an average molecular weight of 18,000 to20,000. The resulting product is vastly improved in its oxidativestability.

22 EXAMPLE 42 To 10,000 parts of a polyethylene having an averagemolecular weight of about 100,000 and which has a tensile strength of5400 p.s.i., a Shore D hardness of 70 and a softening temperature of C.under low load, is added 10 parts of3,5-di-tert-butyl-4-hydroxybenzyloxy'- hydroxyethane to prepare acomposition of outstanding oxidative stability.

EXAMPLE 43 To a polyisobutylene polymer having an average molecularweight of 35,000 is added sufficientbis(3,5-di-tertbutyl-4-hydroxybenzyloxy)ethane to give a compositioncontaining 0.03 percent of the antioxidant. The composition has improvedantioxidant properties due to the presence of4,4'-bis(2,6-diisopropylphenol).

In addition to a product of this invention, the saturated hydrocarbonpolymers of this invention may contain other compounding and coloringadditives including minor proportions of carbon black, elastomers,polyvinyl compounds, carboxylic acid esters, urea-aldehyde condensationproducts, flame retarding agents such as antimony trioxide andchlorinated hydrocarbons and various pigment compositions designed toimpart color to the finished product.

While R and R of Formula I have been described without substituentsattached thereto it is to be understood that this invention is notrestricted to those compounds which are only unsubstituted in thosepositions but extends also to those compounds where R and R havesubstituents such as halogen and nitro groups.

I claim:

1. Organic material normally susceptible to oxidative deteriorationcontaining, as an antioxidant therefor, an antioxidant amount of acompound having the formula:

(I) Ra R1 :l l X2 5 atoms; R R and R are selected from the grouconsistmg of hydrogen and radicals having the formula:

X X X and X, are selected from the group consisting of oxygen andsulfur; a and b are integers having the value 0 to l; and R is analiphatic hydrocarbon radical of from 2-6 carbon atoms and is divalentwhen a and b are 0, trivalent when a plus b is l and tetravalent when aplus b is 2, said valencies being on different carbon atoms.

2. The composition of claim 1 wherein said compound isbis(3,5-di-tert-butyl-4-hydroxybenzyloxy)ethane.

3. The composition of claim 1 wherein said compound is3,5-di-tert-butyl-4-hydroxybenzyloxyhydroxyethane.

4. The composition of claim 1 wherein said organic material is rubber.

5. The composition of claim 4 wherein said compound is his (3 ,5-di-tert-butyl-4-hydroxybenzyloxy ethane.

6. The composition of claim 4 wherein said compound is3,5-di-tert-butyl-4-hydroxybenzyloxyhydroxyethane.

7. The composition of claim 1 wherein said organic material is alubricating oil.

8. The composition of claim 7 wherein said compound is bis 3 ,5-di-tert-butyl-4-hydroxybenzy1oxy) ethane.

9. The composition of claim 7 wherein said compound is3,5-di-tert-butyl-4-hydroxybenzyloxyhydroxyethane.

10. The composition of claim 1 wherein said organic material is apolyolefin.

11. The composition of claim 10 wherein said compound isbis(3,5-di-tert-butyl-4-hydroxybenzyloxy)ethane.

12. The composition of claim 10 wherein said compound is 3,5 ditert-buty1-4-hydroxybenzyloxyhydroxyethane.

13. A composition comprising an organic material normally subject tooxidative deterioration, in intimate admixture with, in amount effectiveto protect said organic material against oxidation, a chemical of theformula:

R R HoQomsxsorn-Q-on It R in which R and R are selected from the groupconsisting of alkyl groups containing up to 12 carbon atoms, cycloalkylgroups containing -8 carbon atoms and aralkyl groups containing from6-11 carbon atoms, and X is a diradical having from 2-6 carbon atoms,the said diradical X being selected from polymethylene diradicals of theformula:

wherein n is a whole number from 2 to 6.

14. A composition as in claim 13 in which the said organic material is arubber.

15. A composition as in claim 13 in which the said organic material ispolypropylene.

16. A composition as in claim 13 in which the said organic material isfat.

17. A composition as in claim 13 in which the said chemical is bis(3alkyl 4-hydroxy-5-alkylbenzylthio)alkane.

18. A composition as in claim 13 in which the said chemical is1,2-bis(3,5-di-tert-butyl-4-hydroxybenzylthio) ethane.

19. A composition comprising an organic material normally subject tooxidative deterioration, containing, in amount sufficient to protect thesaid material against oxidation, a chemical of the formula:

0 H O H in which R and R are selected from the group consisting of alkylgroups of up to 12 carbon atoms, cycloalkyl groups containing 5-8 carbonatoms and aralkyl groups containing from 6-11 carbon atoms, and X is adiradical containing 2-6 carbon atoms, the said diradical X beingselected from poly-methylene diradicals of the formula wherein n is awhole number from 2 to 6.

20. A composition of claim 19 in which the said material is a rubber.

References Cited UNITED STATES PATENTS 3,019,187 1/ 1962 Panzer et a1.25252 3,053,904 9/ 1962 Rocklin. 3,065,275 11/1962 Goddard 26045.953,234,177 2/1966 Van Schooten 26045.95 3,330,804 7/1967 OShea 260'45.953,331,792 7/1967 OShea. 3,010,937 11/1961 Roos et a1. 260-4595 HOSEA E.TAYLOR, JR., Primary Examiner US. Cl. X.R.

P0405" UNITED STATES PATENT OFFICE (5/69) CERTIFICATE OF CORRECTIONPatent No. 5 51011127 Dated May 5, 1970 I Calvin J. Worrel It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 2, in Formula I, that portion of the formula reading T should (1X2 a rea X2 a Column 3, in Formula III, that portion of the formulareading should HO read Column 3, lines 50-51, compound should read3-(4-dodecyl)-5- 2-hexyl-4-hydroxybenzyloxymercaptoethane lines 62-63,compound should read 3,5-di-tert-butyl-4-hydroxybenzyloxy hydlroxyethaneColumn 16, line 9, "4207 F." should read ISILIQE'U" Mu I meow m I. m 1W; a 00mm L Auudng 0M m atent! J

